1. Field of the Invention
The present invention relates to a device for detachably coupling first and second connector halves of an electric connector, including a leaf spring having a fitting portion at one end of the leaf spring, by means of said fitting portion the leaf spring is secured to the first connector halves, a locking aperture into which a locking projection formed on a side wall of the second connector half is inserted to couple the first and second connector halves with each other by means of the leaf spring, and an unlocking portion, by pressing said unlocking portion toward a side wall of the first connector half, the leaf spring being deformed such that the locking aperture is removed from the locking projection to release a locking condition of the first and second connector halves.
2. Description of the Related Art
The above mentioned locking device is most conventionally used for a connector which is used in an environment subjected to a high temperature such as an engine room of an automobile. In this case, each of the first and second connector halves includes a housing made of plastics and the locking projection is integrally formed on the housing of the second connector half.
FIG. 1 is a cross sectional view showing a known connector locking device disclosed in Japanese Patent Application Laid-open Publication Toku Kai Hei 3-159078. In FIG. 1, a first connector half 1 and a second connector half 2 are coupled with each other to form an assembly and are locked in a given position by means of a locking leaf spring 3. It should be noted that FIG. 1 shows only a half of the assembly and a second locking leaf spring provided on an opposite side wall of the assembly is not shown. The locking leaf spring 3 is formed by punching out of a metal plate and is shaped into a desired configuration. The leaf spring 3 comprises a fitting portion 4 at its one end and a locking aperture 5 at the other end thereof. The fitting portion 4 is inserted into a recess formed in a housing of the first connector half 1. On a housing of the second connector half 2 there is formed a locking projection 6. In the coupled condition illustrated in FIG. 1, the locking projection 6 is inserted into the locking aperture 5 of the leaf spring 3, so that the first and second connector halves 1 and 2 are locked by the engagement of the locking aperture 5 and locking projection 6. The leaf spring 3 further includes an intermediate portion 7 and an unlocking portion 8. When the unlocking portion 8 of the leaf spring 3 is pressed upward in FIG. 1, i.e. toward the side wall of the first connector half 1, the leaf spring is deformed as shown by a chain line and the locking projection 6 is removed from the locking aperture 5. That is to say, when the unlocking portion 8 of the leaf spring 3 is pressed toward the side wall of the first connector half 1, the intermediate portion 7 of the leaf spring 3 is urged against a fulcrum portion 9 formed in the housing of the first connector half 1, so that the end of the leaf spring 3 where the locking aperture 5 is formed is effectively moved away from the side wall of the housing of the second connector half 2. In this manner, a portion of the leaf spring 3 including the locking aperture 5, intermediate portion 7 and unlocking portion 8 serves as a lever.
As depicted in FIG. 1, the leaf spring 3 is bent over between the fitting portion 4 and the unlocking portion 8 by a substantially 360 degrees to form a bent portion 10, so that the bent portion is subjected to a large stress. When the unlocking portion 8 of the leaf spring 3 is pressed toward the first connector half 1 in order to disengage the first and second connector halves 1 and 2 from each other, the bent portion 10 is further bent. Therefore, when the locking and unlocking operations is repeated, the mechanical strength of the bent portion 10 of the leaf spring 3 becomes weak. This results in that when the unlocking portion 8 is pressed, the unlocking portion itself is deformed largely and the end portion of the leaf spring 3 at which the locking aperture 5 is formed could not be displaced away from the second connector half 2 and thus the locking condition could not be released positively. Moreover, in the known connector locking device shown in FIG. 1, the unlocking portion 8 of the leaf spring 3 is exposed from the housing of the first connector half 1, so that the unlocking portion is liable to be pressed accidentally. Therefore, it is difficult to attain the positive locking function.
Another locking device is disclosed in Japanese Patent Application Laid-open Publication Toku Kai Hei 4-220974 (EUROPAISCHE PATENTANMELDUNG 446467 A1). The locking device also involves same problems as the above mentioned locking device.